St. Louis County Prosecuting Attorney Robert McCulloch (Tom Gannam/AP)

It could take until October for the grand jury to hear all of the evidence related to the Michael Brown shooting, St. Louis County Prosecutor Robert McCulloch said Wednesday.

“We will present absolutely everything to this grand jury,” McCulloch said during a morning interview with the radio station 550-KTRS in St. Louis.

But not everything is ready to be presented before the grand jury, McCulloch said. Prosecutors hope to have presented all of their evidence by “the middle of October,” he said.

A grand jury is set to begin hearing evidence related to Michael Brown’s death Wednesday. It is still unclear whether Darren Wilson, the Ferguson police officer who shot and killed Brown, will face charges. The standing St. Louis County grand jury, which typically serves for three or four months, will decide whether Wilson should be indicted on any criminal charges. This grand jury is in session until September, but their term will be extended just for this case, McCulloch said.

McCulloch has previously said there would be no timeline for the investigation and said the final decision would be up to the grand jury. “I can’t guarantee and won’t guarantee any particular outcome on the investigation,” he said during a news conference last week.

During the interview Wednesday, McCulloch also criticized Gov. Jay Nixon (D) for Nixon’s comments regarding whether McCulloch should recuse himself from the case. Leaders and residents in the community have called for McCulloch to step aside and allow a special prosecutor to oversee the investigation. St. Louis County Executive Charlie Dooley and State Sen. Jamilah Nasheed (D-St. Louis) have both cited concerns among the black community about McCulloch’s objectivity.

His critics have pointed to his history in explaining why the prosecutor should recuse himself. McCulloch’s father, a white police officer in St. Louis, was shot and killed by a black man in the line of duty when McCulloch was 12. In 2000, he oversaw an investigation into two white police officers who shot and killed two black men; after a grand jury declined to indict them, McCulloch said he agreed with that decision. And more recently, McCulloch publicly lambasted Nixon for putting the State Hi ghway Patrol in control of Ferguson’s security last week, saying the move could “put a lot of people in danger.”

Nixon issued a statement Tuesday evening that he would not ask McCulloch to recuse himself, though he did not offer the prosecutor a ringing endorsement.

“There is a well-established process by which a prosecutor can recuse themselves from a pending investigation, and a special prosecutor be appointed,” he said in the statement. Not following this process “could unnecessarily inject legal uncertainty into this matter and potentially jeopardize the prosecution,” Nixon said.

During his radio interview Wednesday morning, McCulloch reiterated that he had no plans to hand off the case.

“I have absolutely no intention of walking away from the duties and the responsibilities entrusted to me by the people of this community,” McCulloch said. “I’ve done it for 24 years. I’ve done, if I say so myself, a very good job at that. I’m fair and impartial in every matter that comes before us.”

Nixon also said Tuesday that “a vigorous prosecution must now be pursued,” a comment that was criticized by Missouri Lt. Gov. Peter Kinder (R) on Tuesday night.